1. Field of the Invention:
This invention relates generally to an internal combustion engine of the type having an auxiliary combustion chamber in addition to a main combustion chamber, and more particularly to an internal combustion engine as characterized herein which has a hydraulic circuit for controlling the opening and closing operations of an intake valve or valves of the auxiliary combustion chamber or chambers.
2. Description of the Prior Art:
In internal combustion engines having an auxiliary combustion chamber in addition to a main combustion chamber, it has been the conventional practice to provide a mechanical valve operating mechanism for controlling the opening and closing operations of the intake valves of the auxiliary combustion chambers separately from the valve operating mechanism for the intake and exhaust valves of the main combustion chamber, or to modify the valve operating mechanism of the main combustion chamber so as to simultaneously control the opening and closing operation of the intake valves of the respective auxiliary combustion chambers.
Where an independent mechanical valve operating mechanism is employed for the control of the opening and closing operations of the intake valves of the auxiliary combustion chambers, it is necessary to mount the mechanical valve operating mechanism separately from and independently of the mechanical valve operating mechanism of the main combustion chamber. However, this imposes various limitations on the engine design, since the rotational driving force of the engine has to be transmitted mechanically to the valve operating mechanism of the auxiliary combustion chambers through a crank shaft or a shaft which is driven by the main crankshaft or by a chain or gear driving the valve operating mechanism of the main combustion chamber. Furthermore, it is extremely difficult to dispose the valve operating mechanism in the limited space between the cylinder head and the head cover of the engine. As a result, it is difficult to locate the auxiliary combustion chamber in an optimum position relative to the main combustion chamber from the standpoint of combustion. In addition, the internal combustion engine having an auxiliary chamber has a design or construction completely different from ordinary internal combustion engines, which have only the main combustion chambers, and also requires many new component parts, including camshafts, rocker arms and the like, such that development thereof requires a vast investment in the way of production facilities.
In case the valve operating mechanism for the main combustion chamber is modified to simultaneously control the opening and closing operations of the intake valve of the auxiliary combustion chamber, such great changes in structural design are unnecessary, but the problem of spatial limitation for the location of the auxiliary combustion chamber becomes even more severe and other similar problems also arise.
The mechanical valve control has other inherent drawbacks in addition to those which are mentioned hereinbefore. For example, it is difficult to vary the lifting or open period of the intake valve, such that the variable mechanism of complicated construction and high precision is required. Furthermore, by means of the mechanical valve control, it is almost impossible to hold the intake valve continuously in a closed or open position under certain operating conditions of the engine, such as, for example, under engine braking conditions or at the time of sudden acceleration conditions, and so forth.